In many systems, for example, UWB systems that follow the WiMedia standard (an ISO-published radio platform standard for high-speed ultra wideband (UWB) wireless connectivity), specific local oscillator (LO) frequency characteristics are required or desirable. For example, to implement the WiMedia standard, at least 3 LO frequencies must be generated per band group. The number of required LO frequencies increases when the system supports multiple band groups. The system must be able to switch between the band groups within 300 ns and must be able to hop among the 3 LO frequencies in a band group in less than 10 ns. There are also phase coherency requirements when hopping between frequencies.
Approaches such as switching the reference frequency of a phase-locked loop (PLL), using a digital PLL with a digital controlled oscillator (DCO), and/or storing the frequency information of the DCO for fast-hopping will not provide the required UWB LO signals.